The treatment of low-grade upper tract urothelial carcinomas (UTUCs) after either surgery, or nephron-sparing techniques remains an unmet need in Genitourinary (GU) Oncology. UGN-101 is a novel drug in development for the treatment of UTUCs; it is composed of a sustained-release hydrogel polymer-based formulation containing the antitumor antibiotic mitomycin-C (MM-C); cold UGN-101 is liquid, but at body temperature, it becomes a gel, and thus, when administered through a ureteral catheter, it sticks to the upper tract urothelium, slowly releasing MM-C.